Los Angeles - Crews cleared mud from the streets of foothill suburbs below a wildfire-stripped mountainside as the first in a series of Pacific storms moved through Southern California on Friday.

Off the coast, searchers on Santa Catalina Island found the wreck of a small plane that disappeared with three people aboard after takeoff as the storm arrived Thursday evening. The pilot and two passengers were dead.

Mount Baldy, towering more than 10,000 feet northeast of Los Angeles reported up to a foot of snow by Friday evening and the National Weather Service said the snow level in the mountains could lower to 4,000 feet and the major Interstate 5 corridor could be affected Saturday.

In Sierra Madre, east of Los Angeles, work crews and residents spent the day clearing a muddy mess that flowed down from steep slopes of the San Gabriel Mountains left bare by a wildfire last April.

Public works director Bruce Inman said two streets were closed for debris removal and one home was evacuated. One street was reopened by evening.

The city was maintaining a "yellow flag alert" based on mudflow forecasts. Among its effects, the alert bars parking in areas of potential mud runoff. The California Conservation Corps said it sent two 30-member crews to help.

On Catalina, it was not immediately known if the fatal plane crash was caused by bad weather.

A Coast Guard statement said the Bonanza airplane, flown by pilot Mark Hogland, was last seen leaving the island around 5 p.m. Thursday, headed for John Wayne Airport in Orange County. The Coast Guard said the pilot didn't make a distress call.

The plane was reported missing by the pilot's fiancee that evening and it was located in a remote area on the island's west end at midmorning Friday. Federal Aviation Administration spokesman Ian Gregor said the plane was registered to SkyBlue USA.

The Dana Point company's Web site lists Hogland as the president and CEO and says it provides sightseeing tours to Catalina and other locations.

The NWS said a cold upper-level low-pressure system centered off the state's central coast was moving southward and isolated severe weather was possible through early Saturday, including thunderstorms, gusty winds, hail and lightning.

"Conditions will also become more favorable for rotating storms, bringing the possibility of waterspout and funnel cloud activity as well as isolated small tornadoes across coastal areas," the NWS said.

A flash flood watch was in effect for Southern California wildfire burn areas through noon Saturday.